The present invention relates to a device for obtaining a sample of liquid from the bottom of a liquid-filled container. More particularly, the invention relates to a device for obtaining a sample of water or water-oil emulsion from underneath the crude oil in the cargo tank of an oil tanker.
In many instances, cargo oil, e.g. crude or refined oil which is loaded onto tankers is contaminated with substantial amounts of water. If payment for the oil is based on the measured volume of total liquid in the cargo tanks, the final cost to a buyer may be higher than it should be because he pays for the useless water at cargo oil prices. In many actual cargo oil purchasing situations, the buyer is allowed to deduct the volume of water in the cargo tanks only if he can prove that it was pumped aboard with the cargo oil and was not already present in the tanks before the cargo oil was loaded.
Since water inadvertently left in the tanks (e.g. seawater used for ballast, etc.), will have a substantially different composition from the water loaded with the cargo oil (e.g. formation water produced with the crude or condensate from steam used in processing the produced oil,), the origin of the water in question can readily be established if a sample of the water can be obtained from a cargo tank for analysis after it has been loaded.
Further, by knowing the origin of any water in a loaded cargo tank, steps can be taken to alleviate the contamination problem. That is, if the water is being pumped in with the cargo oil, further processing of the cargo oil can be undertaken to remove the water before loading or if the water is originally present in the tank, further steps can be taken aboard the ship to remove such water before loading.